Name: Make-Ahead Southwest Breakfast Casserole with Peppers and Onions Recipe
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Cuisine: Southwestern American
Ingredients: 1 pound ground breakfast sausage (use your favorite!); 1 red bell pepper, diced; 1 green bell pepper, diced; 1 yellow onion, finely diced; 2 cloves garlic, minced; Olive oil, for cooking; Kosher salt and freshly ground black pepper, to taste; 1 teaspoon smoked paprika; ½ teaspoon chili powder; ½ teaspoon cumin; 12 large eggs; 1 ¼ cups half-and-half (or whole milk); 1 ¼ teaspoon kosher salt; ½ teaspoon freshly ground black pepper; 2 cups shredded sharp cheddar cheese (or a mix of cheddar + Monterey Jack), divided; 2 tablespoons fresh cilantro, chopped

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If you love starting your day with a burst of flavor and a dish that can be prepared ahead of time, you are going to adore this Make-Ahead Southwest Breakfast Casserole with Peppers and Onions Recipe. It brings together fluffy eggs, a vibrant trio of sweet peppers and onions, and savory sausage, making each bite a balanced mix of hearty and fresh. Whether it’s a busy weekday morning or a relaxed weekend brunch, this casserole is a warm, satisfying hug on a plate that you can prep in advance and enjoy without fuss.

Ingredients You’ll Need

The image shows a top view of cooking ingredients neatly arranged on a white marbled surface. There are 10 brown eggs in a carton in the center left. To the left of the eggs is a small glass bowl with chopped white onions and below it a white plate with four different ground spices in small piles showing red, brown, dark red, and light brown colors. Centered is a glass bowl with raw ground meat that has a pink and white mix. Surrounding this are four small glass bowls: one with chopped green bell peppers at the top, one with chopped red bell peppers at the bottom right, one with shredded orange cheddar cheese on the middle right, and one small bowl with two garlic cloves below the cheese. A glass measuring cup with white milk is placed above the cheese bowl. In between the meat and the red pepper is a small bunch of green cilantro leaves. The overall look is clean with bright natural lighting. Photo taken with an iphone --ar 4:5 --v 7

Gathering your ingredients is the first step to a fuss-free and delicious breakfast casserole. Each element plays its part— from the savory sausage adding rich depth, to the colorful peppers and onions creating a sweet and tender bite, all the way to the creamy eggs that hold everything together in perfect harmony.

1 pound ground breakfast sausage: Choose your favorite type, as it brings the essential savory base to this casserole.

1 red bell pepper, diced: Adds a pop of sweet color and crisp texture to brighten the dish.
1 green bell pepper, diced: Provides a fresh, slightly grassy contrast balancing the sweetness.
1 yellow onion, finely diced: Offers natural sweetness and depth of flavor when sautéed.

2 cloves garlic, minced: Brings a fragrant, savory zing that lifts the entire casserole.
1 teaspoon smoked paprika: Infuses a smoky warmth that’s key to that southwest flavor profile.
½ teaspoon chili powder: Introduces mild heat and complexity to the seasoning blend.

½ teaspoon cumin: Adds an earthy, nutty undertone that complements the southwest theme.
12 large eggs: The fluffy, custardy backbone of the casserole, binding all ingredients together.
1 ¼ cups half-and-half (or whole milk): Creates a creamy texture and tender consistency in the eggs.

2 cups shredded sharp cheddar cheese: Or a mix with Monterey Jack for creaminess and sharpness.
2 tablespoons fresh cilantro, chopped: Offers a bright herbal finish that adds freshness.
Olive oil, for cooking: Enhances sautéing and prevents sticking without overpowering flavors.

Kosher salt and freshly ground black pepper, to taste: To season perfectly and bring out every ingredient’s best.

How to Make Make-Ahead Southwest Breakfast Casserole with Peppers and Onions Recipe

Step 1: Brown the Sausage

Start by heating a large skillet over medium-high heat. Add your ground breakfast sausage and cook it until it’s nice and browned with a crumbly texture, about 6 to 7 minutes. This step is essential because it develops the deep, savory flavor that forms the heart of your casserole. Once cooked, transfer the sausage to a plate and set it aside to keep warm.

Step 2: Sauté the Peppers and Onions

In the same skillet, drizzle a little olive oil if the pan looks a bit dry. Now add your diced red and green bell peppers along with the finely diced yellow onion. Cook these together for 5 to 6 minutes until they soften and start to release their natural sweetness. Season lightly with salt and pepper. Then stir in the minced garlic and the fabulous trio of smoked paprika, chili powder, and cumin—let this saute for about 1 minute until all those flavors bloom and your kitchen smells irresistible.

Step 3: Prepare the Baking Dish

Grease a 9×13-inch baking dish generously with a little olive oil or non-stick spray. Spread the cooked sausage evenly across the bottom, followed by the sautéed pepper and onion mixture. This layering ensures every slice of your casserole has a balanced bite of meat and veggies.

Step 4: Whisk and Combine the Egg Mixture

In a large bowl, whisk together your 12 eggs and 1 ¼ cups of half-and-half (or whole milk) until smooth. Season with 1 ¼ teaspoons kosher salt and ½ teaspoon freshly ground black pepper for perfect seasoning. Stir in half of your shredded cheese to infuse the mixture with cheesy goodness. Pour this creamy egg blend evenly over the sausage and veggie base, making sure it reaches all corners for even cooking.

Step 5: Add the Final Cheese and Bake

Sprinkle the remaining cheese evenly on top to create a golden, bubbly crust. Bake your Make-Ahead Southwest Breakfast Casserole with Peppers and Onions Recipe in a preheated oven at 375°F (190°C) for 25 to 30 minutes. You want the eggs just about set in the center with the top turning a beautiful golden hue. Remove the casserole from the oven the moment the center feels firm but not jiggly; it will continue to cook slightly as it rests.

Step 6: Rest and Garnish

Allow the casserole to rest for 5 to 10 minutes after baking. This pause lets everything settle perfectly, so when you slice it, each piece holds together nicely. Finish by sprinkling fresh chopped cilantro on top—this fresh and vibrant herb adds the perfect southwest flair to your dish.

How to Serve Make-Ahead Southwest Breakfast Casserole with Peppers and Onions Recipe

The image shows a white baking dish with two visible layers inside; the first layer is a mix of cooked ground meat and diced red and green bell peppers spread evenly at the bottom, showing a slightly browned and textured look. The second layer is a creamy yellowish sauce with small bits of orange shredded cheese and black pepper specks being poured over the meat and pepper layer from a clear glass bowl held by a woman's hand in the lower right corner. The dish sits on a white marbled surface, creating a clean and bright setting. Photo taken with an iphone --ar 4:5 --v 7

Garnishes

Sprinkle extra fresh cilantro or chopped green onions on top right before serving for an added fresh brightness. If you like a little heat, a dollop of salsa, sliced avocado, or a spoonful of sour cream can elevate this dish into something truly spectacular.

Side Dishes

This casserole pairs beautifully with light sides like fresh fruit salad, crispy breakfast potatoes, or even a simple green salad to balance the richness. For a heartier meal, add warm tortillas or crusty bread to scoop up every last bite.

Creative Ways to Present

Try turning leftovers into breakfast burritos by wrapping slices in warm tortillas with extra cheese and salsa. Or, if entertaining, serve the casserole buffet-style with a variety of toppings and small bowls of salsas, guacamole, and sour cream so guests can customize their plates.

Make Ahead and Storage

Storing Leftovers

After enjoying your casserole, wrap any leftovers tightly with plastic wrap or place them in an airtight container and refrigerate. They will keep well for up to four days, making for quick, delicious breakfasts without any extra effort.

Freezing

This Make-Ahead Southwest Breakfast Casserole with Peppers and Onions Recipe freezes beautifully. Wrap it tightly in foil and then place it in a freezer bag to prevent freezer burn. It will keep its lovely texture and flavor for up to two months, making it a perfect meal prep winner.

Reheating

To reheat, thaw overnight in the refrigerator or heat from frozen at a low temperature. For the best texture, use a 350°F (175°C) oven and cover the dish loosely with foil until warmed through, about 15–20 minutes. Microwave reheating works too, but the oven method preserves the casserole’s delightful crust.

FAQs

Can I make this casserole vegetarian?

Absolutely! Simply leave out the sausage and add extra vegetables like mushrooms, zucchini, or black beans for a delicious vegetarian version that’s just as satisfying and flavorful.

What can I use if I don’t have half-and-half?

You can replace half-and-half with whole milk or a combination of milk and a bit of cream. For a dairy-free option, use your favorite plant-based milk and skip the cheese or use a dairy-free cheese alternative.

Is this recipe gluten-free?

Yes, it’s naturally gluten-free. Just be sure to check your sausage and cheese labels to avoid any hidden gluten-containing additives.

Can I add other types of cheese?

Definitely! Monterey Jack, Pepper Jack, or even a Mexican blend work wonderfully. Mix and match cheeses to find your favorite flavor combination.

How far ahead can I prepare this casserole?

You can assemble the casserole up to 24 hours ahead of time and keep it covered in the fridge. When ready, bake as instructed, adding a few extra minutes if it’s cold out of the fridge.

Final Thoughts

This Make-Ahead Southwest Breakfast Casserole with Peppers and Onions Recipe is a delicious and practical way to brighten your mornings, impress brunch guests, or simply enjoy a fuss-free hearty meal any day of the week. With its vibrant flavors and easy prep, it’s sure to become a beloved staple in your kitchen. Give it a try and watch it quickly become a favorite in your breakfast rotation!